1. Field of the Invention
The present invention relates to an electronic device and a touch display of the electronic device. More particularly, the present invention relates to a touch display with a grounding shield integrated in the touch display.
2. Description of the Related Art
FIG. 1 is a schematic view from above of a part of a conventional touch display panel 100. The touch sensor may be capacitance type touch sensor with a pair of electrodes disposed to face each other with a dielectric body in between. Please refer to FIG. 2 for the drive line 110 as a first electrode and the sense line 120 as a second electrode. The display panel 100 further includes a transmitting circuit 130. The transmitting circuitry 130 is coupled to the drive lines and scans the drive lines by distributing a touch driving signal to each drive line according to a preset sequence. The sense lines generate a sense signal in response to the touch driving signal. It is achieved by transmitting the touch driving signal to the drive line to generate electric field and the sense line receives the energy of the electric filed and generates the sense signal. The sense signal may be analyzed by an external circuitry to calculate the touch position of the user on the touch display 100.
FIG. 2 is a cross-sectional view of the AA′ line in FIG. 1. The touch display panel 100 further includes a first substrate 14, a liquid crystal layer 16, a color filter layer 12a, and a second substrate 12. The plurality of sense lines (the second electrodes) are disposed on the second substrate 12. The plurality of drive lines (the first electrodes) are disposed between the liquid crystal layer 16 and the first substrate 14. The plurality of drive lines and the plurality of sense lines constitute a capacitive touch sensor integrated in the touch display panel 100. The transmitting circuit 130 is disposed on at least one side of the drive line to transmit the touch driving signal to the drive line.
FIG. 3 is a schematic diagram showing the electrical field in a part of the display panel 100. When the transmitting circuit 130 scans the drive lines, a normal electric field 161 is generated by the drive line 110, and the sense line 120 received the energy generated by the normal electric field 161 and generates the sense signal. The transmitting circuit 130 transmitting the touch driving signal to the drive line may generated another electrode field that may be received by the sense electrode 120 as the fringe electric field 162 formed between the transmitting circuit 130 and the sense line 120. The normal electric field 161 and the fringe electric field 162 are depicted by two types of dotted lines in FIG. 3, respectively.
The normal electric field 161 appears only when the transmitting circuit 130 sends the touch driving signal to the drive line 110. The normal electric field 161 does not appear when the transmitting circuit 130 sends the touch driving signal to the other drive lines. The normal electric field 161 is mandatory for the touch detection around the drive line 110. Assume that the fringe electric field 162 does not exist and there is only the normal electric field 161. The electrical environment changes when a human hand enters the normal electric field 161, with a portion of the electric field being directed to ground instead of terminating at the sense line 120. The sense signal reflects the resultant decrease in capacitance so that the touch of the user can be detected.
On the other hand, the fringe electric field 162 originates in the intense AC driving signal in the transmitting circuit 130. The fringe electric field 162 appears when the transmitting circuitry 130 sends the touch driving signal to the drive line 110 or another nearby drive line. The fringe electric field 162 is undesirable because the fringe electric field 162 affects the field strength at the sense line 120 and interferes with the sense signal, which induces erroneous results of touch detection.